1. Field of the Invention
The present invention relates to oil field tools, and in particular to an abrading tool used down in the hole or well; and more particularly to a tool for abrading a cable or other similar item positioned on the exterior of a well tubing located down in the hole of the well, usually within an exterior well casing, so that the cable may be severed.
2. Prior Art and General Background
In the oil field oil wells are drilled deeply down into the ground. Typically a casing is included to form an interior steel wall for the hole. Within the hole long lengths of primary tubing are lowered during various times as needed during the drilling or operation of the well.
In particular, many long lengths of tubing, made up of individual sections, are lowered down into the hole with some exterior material, such as for example a cable wrapped along its exterior, usually extending down to the bottom end portion of the tubing. In certain circumstances, the major length of the tubing needs to be withdrawn, while the very bottom, end portion is cut away and at least temporarily left down in the hole. This may occur for example when a packer or electric pump down toward the end of the tubing gets lodged or stuck in the hole.
A problem arises in such a situation due to the cable extending down and being attached to the portion of the tubing to be left in the hole. In order to withdraw the greater length of the tubing, the cable needs to be broken or otherwise severed in order to allow such withdrawal. If the upper tool portion is merely pulled up until the cable snaps or breaks somewhere along its length, which for example could occur many feet above the "abandoned" lower section of the tubing, a big pile of cabling then falls down on top of the "abandoned" section, blocking access to it and causing a difficult problem should thereafter one desire to remove or retrieve the "abandoned" section by jarring or forcible pulling it loose.
In general, an attempt to cut the cable by using a suitable casing cutter is not successful due to the difference in cutting a relatively loose cable, as compared to cutting rigid, fixed casing, which may be cut by a blade striking an arc along the inside of the casing or concentric tubing as the blade is positioned radially outward and rotated. As may be appreciated, with casing or tubing the blade may not be moved radially outward a radial distance further than the interior wall of the tubing or casing, resulting in the cutting tip of the blade having a correct position for cutting the casing or tubing. However, with a flexible, relatively loose cable, the cutting tip would generally be extended radially past the cable. When the casing cutter is rotated, this results in the blade bumping into the cable and then refusing to rotate due to blocking by the cable, or, if the rotating torque is high enough, putting the cable in high tension and causing the cable to eventually snap, which may occur anywhere along its length.
Applicant knows of no suitable tool which may be used for cutting cable down-hole. Accordingly, the present invention is directed to an oil field cable abrader which can be lowered down within the tubing down to the area where the tubing has been cut by other suitable means, and which may then be used to sever the exposed cable on the exterior of the primary tubing by abrading the cable. In order that abrading may occur, the cable abrader of the present invention provides a spiraling abrasive path over which the cable may be drawn as the cable abrader is rotated until the cable is severed, allowing the primary tubing to be then withdrawn without interference from the cable or leaving a large amount of cabling on top of the bottom end portion of the tubing left in the hole.
3. General Discussion of the Invention
It is thus a basic object of the present invention to provide a safe, reliable, economical, practical tool for abrading cable or other such material on the exterior of a tubing substantially down in the hole, typically with a tool which in a series of either rotational (preferred) or longitudinal passes ultimately severs the cable.
The present invention in its preferred embodiment achieves these goals by utilizing a basic abrading body located at the end of a smaller diameter tubing which is lowered down within the interior of a primary tubing which may be concentrically located within a casing. The abrading body includes an abrading head (with spirally located abrading elements) pivotally connected to the lower end of the tool body, which abrading head hangs down in a vertical disposition due to its own weight as the abrading tool is lowered into the primary tubing.
However, when the abrading tool of the invention reaches the area where the exterior cable is exposed, fluid pressure from the surface is used to push down a piston slidably disposed within the interior of the abrading body, causing the abrading head to be pivoted laterally out about its pivotal connection to a position suitable to make contact with the exposed, exterior cable.
The tool is then rotated about a vertical axis causing the abrading head to cyclically abrade and, after a sufficient number of passes, sever the cable. The present invention accomplishes this by wrapping the cable at least partially around an abrading portion on the head, which portion spirals about the abrading head to provide a curved path on the abrading head over which the cable is drawn or dragged and abraded cyclically until the cable is ultimately severed.
Upon completion of the job, the interior fluid pressure is relieved, causing the abrading head under its own weight to return back down to its retracted, vertical disposition, allowing the abrading tool of the present invention and its smaller diameter tubing to be withdrawn out of the primary tubing and the hole.
With the severance of the exterior cable, the upper, main length of the primary tubing with the severed portion of the cable wrapped around it or otherwise attached to it can then likewise be withdrawn up out of the hole, leaving the other, relatively short severed portion of the cable down in the hole with its attendant element(s).